dtype({'names': ['f0', 'f1', 'f2'], 'formats': ['u1', '<i8', '<f8'], 'offsets': [0, 8, 16], 'itemsize': 24}, align=True)
    >>> print_offsets(dt)
    offsets: [0, 8, 16]
    itemsize: 24
    >>> packed_dt = rfn.repack_fields(dt)
    >>> packed_dt
    dtype([('f0', 'u1'), ('f1', '<i8'), ('f2', '<f8')])
    >>> print_offsets(packed_dt)
    offsets: [0, 1, 9]
    itemsize: 17

    )